Perhaps you should try some spelling variations:
thong cong » trong cong, tong cong, thong thong
hieu lang » chieu sang, hieu quang, nhieu tang
lanh manh » lanh tranh, lan anh, van manh
cua thong » cua thuong, cua khong, cua tong
thanh cha » thanh ha, thanh nha, thanh phan
doc hieu » toc thieu, hoc thieu, hoc hien
manh cua » doanh cua, ban cua
cong tan » cong tac, cong san, cong thanh
khan cap » khan ap, than cap, khoan cam

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu lang - lanh manh cua thong cong tan ((thanh cha) OR (khan cap))~.
• Adding a wildcard symbol may retrieve word variants: doc hieu lang - lanh manh cua thong cong tan ((thanh cha) or (khan cap))*.